Fixed|Server: Crash when hit-testing mobjs

A call was being made to a client-only API.
Fixed|Server: Sounds emitted by sectors

When a sound was emitted by a sector (not a plane), the client was not
up to speed about which sound origin to use.
Fixed|Server|Hexen: Sound sequences not played (e.g., door creak)

On the server, no one was calling the sound sequence update function,
which caused the sequences to be not played.
Server|Debug: Moved debug message to a lower level
Revert "Fixed|Server: Crash when hit-testing mobjs"

This reverts commit 544f6eed30a8daed6d196f09a19236206d4fb06a.
Fixed|Server: Crash when hit-testing mobjs

A call was being made to a client-only API.

Note: __CLIENT__ is not defined in plugins (libcommon).